1. Field of the Invention
The present invention relates generally to spark ignition systems for use in combustion devices, e.g., reciprocating engines, furnaces, etc. More specifically, the present invention comprises various embodiments of an ignition device that spans a combustion chamber volume, with the ignition spark occurring in the general center of the combustion chamber volume.
2. Description of the Related Art
Electrical or spark ignition systems for various types of combustion devices are extremely well known. Such spark ignition systems are commonly used to ignite the fuel/air mixture in reciprocating engines, as well as other types of engines. Such spark ignition systems are also used in heater combustors, furnaces, and various other devices that burn fuel to produce heat.
The ignitors (e.g., spark plugs) used in such devices are nearly universally located in the wall of the combustion chamber, where wiring and access to the ignitor is facilitated. However, this generally results in less than optimum ignition and burning of the air/fuel mixture within the combustion chamber, due to the peripheral location of the ignition source in comparison to the central volume of the combustion chamber. The peripheral location of the ignition source generally necessitates a richer fuel mixture due to the displaced position of the ignition source from its optimal center position, as well as resulting in increases in emissions and less than optimum efficiency, i.e., poorer fuel mileage than the ideal in a motor vehicle.
The need for a centralized location for the ignition source is especially critical in certain types of reciprocating engines. An example of such is found in U.S. Patent Publication No. 2004/221,823 published on Nov. 11, 2004 to the present inventor, titled “Opposed Piston Engine,” now issued as U.S. Pat. No. 7,004,120 on Feb. 28, 2006, the disclosure of which is hereby incorporated by reference in its entirety. This engine is structured with a single common combustion chamber for each pair of opposed pistons, with the opposed pistons driving a pair of opposed crankshafts at the outer sides of the engine. An ignition source spans the center of each combustion chamber, with the spark traveling between the ignition source and a protuberance extending from the center of the piston. In contrast, the present ignition system does not rely upon another moving component to provide a continuation of the electrical path, but rather uses a conductor spanning the combustion chamber and having a spark gap therein to produce the generally centrally located ignition spark.
The present inventor is also aware of other spark ignition devices that serve to ignite a fuel/air mixture within a combustion chamber. Japanese Patent No. 1-150,709, published on Jun. 13, 1989, describes (according to the drawings and English abstract) a burner having an axial ignition conductor extending therethrough to a ground ring surrounding the end of the conductor. The ground ring is located in a foraminous ceramic diffuser. A spark jumping the gap between the tip of the conductor and the ground ring ignites the gas mixture flowing through the ceramic diffuser. The device does not span the general center of the combustion chamber, but rather is located in one wall of the combustion chamber as defined by the ceramic diffuser.
Finally, Japanese Patent No. 2005-129,396, published on May 19, 2005, describes (according to the drawings and English abstract) a gas burner having an electrical ignitor therein. The ignitor is shown to be offset from the center of the device in the detail view of FIG. 5 of this reference, and does not span the diameter of the combustion chamber.
Thus, a centrally located ignition source in a combustion chamber solving the aforementioned problems is desired.